From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit bdd65589593edd79b6a12ce86b3b7a7c6dae5208 upstream.
0day reported a possible circular locking dependency:
Chain exists of:
&irq_desc_lock_class --> console_owner --> &port_lock_key
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&port_lock_key);
lock(console_owner);
lock(&port_lock_key);
lock(&irq_desc_lock_class);
The reason for this is a printk() in the i8259 interrupt chip driver
which is invoked with the irq descriptor lock held, which reverses the
lock operations vs. printk() from arbitrary contexts.
Switch the printk() to printk_deferred() to avoid that.
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/87365abt2v.fsf@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/i8259.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/i8259.c
+++ b/arch/x86/kernel/i8259.c
@@ -207,7 +207,7 @@ spurious_8259A_irq:
* lets ACK and report it. [once per IRQ]
*/
if (!(spurious_irq_mask & irqmask)) {
- printk(KERN_DEBUG
+ printk_deferred(KERN_DEBUG
"spurious 8259A interrupt: IRQ%d.\n", irq);
spurious_irq_mask |= irqmask;
}
